Free piston pump engine



April 4, 1950 U.-EKBLOM FREE PISTON PUMP ENGINE 5' Sheets-Sheet 1 Filed Jul 3, 1946 mm mm 1 F m U ATTOR NE Y- U. EKBLOM FREE PISTON PUMP ENGINE April 4, 1950 2,503,152

Filed July 3, 1946 5 Sheets-Sheet 2 INVENTOR:

UNU E K BL 5/77 ATTORNEY- April 1950 u. EKBLOM 2,503,152

FREE PISTON PUMP ENGINE INVENTOR."

.UNU E/(BL U/77 a BY 00 ATTOR NEY.

Yi /175m 5 April 4-, 1950 U.'EKBLOM FREE PISTON PUMP ENGINE- H mm a MHZ w E mm 5 N vU Filed July 3, 1946 Patented Apr. 4, 1950 4 UNITED OFFICE.

Faun-PISTON PUMP ENGINE Um Elgblnm, Brooklyn, .N. Y.

'AppIication'JuIyB', 1946', Serial No; 681.3397 8 (erase- 56) "This invention relates to a free piston or oscillatory type of internal combustion engine'which may be classifiedwith- Diesel engines and is advantageously combined directly with a piston pump, generator and/orother pow-ertransmitting or transforming means.

The mainobjectof rn-y invention is" to provide an internal combustion engine of the free piston type which is of such efficient design byelimination of piston rods, crossheads, cranksancl shafts that the major portion of' the frictional losses present in conventional engines is absent.

' An equallyimportant objectis to have such an} engine which when combined with a piston pump designed to cooperate therewith will form with the latter such a light Weight and compact power plant that it is particularly adapted for pneumatic or coil jet propulsion on airplanes and ships where such operation has heretofore never been feasible. Y

Another object is to combine the engine with a special pneumatic pump in order to obtain the full; power of the engine in the form of a supply of compressed" air--01 suction; by directly coinbining the air pump piston with the engine piston without any intervening members, such as shafting', bearings, pulleys, gears, piston rods, cranks, crossheads, chains or bolts.

7 A further objectis to include starting means for the engine and pump apparatus capable of controllingtherunning speed: of the apparatus "as a Whole.

Itis also an object herein to include special valve and piston equipment for producing high compression of the air supplied by the engine a and" pump combination comprising theinvention.

In addition, it isan important object to have a free piston enginewhich by virtue of its simple construction and light form is capable of very high speeds ofoperationand. adjustable compression, with consequent great power output and capacity with respect to any: given size ofengi'ne;

Anancillaryobject is to have a free piston engine of the indicated type in which the power output may be represented by the compressed air, suction, stored water or other fluidor by electric current if electric generation equipment replaces or accompanies the pump piston in actual service.

An-object connected with the starting equipment is to have auxiliary pumping mean-s formed by projections upon the pump piston and correspending recesses inthe pump cylinder without the addition of any parts althoughconstituting independently effective operating means aside 2. from the regular operation or the pump piston as such.

It is likewise an object. of the invention to. $0 mount. the engine slidably upon a proper stationary base that; all vibration tends to be new traliz-ed during operation alt-any: speed. I 1 Other objects and the advantages of the a. rangement, construction and practical application. of my: invention to the. art. will apncar in further detail. as this specification proceeds.-

In order to disclosethe invention in clearly comprehensible the same is illustrated in certain non-limiting forms in the accompany ing drawings forming par-t. hereof, and in which .Eig .;l is an end; elevation ofan internal com-s bustion engine: made according to. certain prins ciplesuoi the present invention and embodying salient. features thereof in a practical for-m; Eig...2: is; a cross. section. of the same engine taken online in Fig. 4, the view being partly exploded to show aradiatcrand manifolds shifted from: their proper positions to disclose detai -l; Fig. 3 is asoction or a manifold. of Fig.2 taken onlsine Rig..- 4; is a. diagrammatic. longitudinal section or; the. same apparatus of Fig. 1:, taken obliquely n ne- 4.-.-4,. approximately;

Fig; a. horizontat longitudinal view in sec, tlon; taken on 5-15 in said Fig. 1*; Fig; Brie a. vertical longitudinal section taken. on line ie fii' in the? same. Fig. 1-; Fig. as well. as: 8a are enlarged detail sections. or an. exhaust driven. rotary Water pump of Figs. and; 4.;-

F1339; is; a longitudinal section ot a modificatinn .oi' the engine. of Figs- 1 and 6., and

y Fig; 10, is amend: View of the. same. modification. Finally-gv Fig... is; an enlarged section: 01% a detail at Fig. 110.. 1 Throughout; the views, the some references. indicate the same or like parts.

It .is a. Sfflfr-EMidBnt; fact: that in order for internal: combustion engines. to. be suitable for aeroplanes, they must necessarily be very light g and" eflicien't; .to some extent. this. goal has: been attained when using such engines to drive: pros pellets and thereby pull or push the aircraft through the atmosphere mechanically; On the other'hand; it has been. found that, jet of gas projected rearwardlw from aircraft are capable of producing high frying: speeds Without any of the intricate mechanism usually iorming the power plant on conventional aircraft, and itis: thus a promising meansof propulsion. f Instead of usine propellers. therefore, or even.

3 highly heated gases for the jets to drive aircraft, it is now proposed to drive such craft with compressed air and even to drive ships in the water by such jets by providing a special free piston internal combustion engine combined with an air pump. The resulting combination is such an extremely light and efiicient unit that the power of the same is converted into an output of compressed air of such volume and force that the air can be used idirectlyflin cool condition-to produce the driving"jets" of "the aircraft equipped with the unit operating according to the well known rocket principle but without heat or flame.

Hence, referring again to the drawings, and with the foregoing objects in view, a free piston engine, generally indicated at H is providedwith a base plate l2 (Figs. 1, 2 andfiiand having a pair of upright end lugs l3, l3 and preferably bolted to the floor l4 Upon this base plate is slidably mounted a plate l5 having lugs l3, l5 secured to the two engine end plates ll, ll, while in the lugs E3 of the base plate a pair of oppositely directed adjusting screws l8; 18 are inserted which at their inner ends engage against shock absorbing springs l9, I9. At their other ends, these screws engage against ends 20,.20' of plate [5 to absorb shocks and vibration of the engine while plate l5 slides upon base plate l2 during operation produced by such vibration. If the springs require to be compressed or released to accurately cushion the vibrations of the engine, the screws l8 are easily adjusted accordingly.

Between the end plates IT, IT is clamped the cylindrical wall member or tube 2 l the plates and said wall member being retained in position in assembly by the rods 22 threadedat the ends and held in place by nuts 23, 23. The members just described define a cylinder within which a plate piston 24 having a piston ring 25 is adapted to reciprocate in a manner which will be set forth presently. On the other hand, upon the two external end plates ill, I? is fixed a pair of opposite cylinders 26, 26' provided with water jackets 21, 21 and being internally of considerably. smaller diameter than cylinder 21.. Within cylinder 25, 23 are slidably mounted hollow pistons 28, 28 which are secured'in line upon piston core 29 which serves as a partition between interior piston chambers 30, 30. The inner ends of pistons 28, 28 clampthe internal flange 3| of plate piston 24 between them so thatv for the purpose of the invention, pistons 28, 28, 24 and core 29 form a reciprocating piston unit in end cylinders 26, 25 and intermediate cylinder 2|, respectively. The larger intermediate cylinder serves for compressing or supplying airforv the engine as well as for outside use, and the smaller end cylinders contain the internal. combustion chambers 32, 32, as will also be explained later In the ends of the combustion chambers are provided hot wire ignition plugs 33, 33' connected to. one or more sources 34, 34' of current controlled by switches35, 35 (Figs. 4 and 5) by which to supply current to the plugs for heating the hot wires 35, 35' thereofl'at will. for starting the engine. As particularly shown in Fig. 4, a fuel tank 31 supplies liquid fuel such as oil or other combustible fluid by way of fuel line 38 and branch lines 39, 39' to injector nozzles 40, 4D controlling the amount of fuel drawn into the end cylinder chambers by pistons 28, 28' by means of manually adjustable needle valves 4|, 4!, while the flow of fuel to fuel line 38 is 4 controlled by manual cutoff valve 42. The fuel nozzles terminate at an inclined angle in the side wall recesses 43, 43 in end cylinders 26, 26' which are alternately cut ofi from communication with chambers 32, 32 by the end pistons 28, 28, the upper end portions 44, 44' being curved to direct the fuel into the respective cylinder chambers from the ends of said pistons. In similar fashion, the ends of the latter are curved also'attheir lower portions 45, 45 to facilitate smooth flow of exhaust gases from the chambers into exhaust pipes 46, 46', of which more later.

' The cylinder chambers just described are supplied with air from the larger adjacent intermediate pump chambers 41, 41 on both sides of piston 24 via the internal chambers 30, 3| of pistons 28, 28', while the ment1oned piston 24 draws in air to be cdmpressed into chamber 41 through intake manifold 48, and inlet slots 49 in semirotary valve plate 50 held slidably against end plate i! by screws 5| and through corresponding intake slots 52 in said plate ll past leaf spring valves 53. In chamber 41 the corresponding parts have corresponding prime references and operate in similar fashion. Adjacent to the larger ends of intake members 48, 48 are fixed radiators 54, 54 connected by pipes 55, 55 to the cylinder water jackets 21, 21' and to rotary pumps 56, 56 driven by the associated exhaust operated motors 51, 51' (Figs. 1, '7 and 8) having their rotors 58, 59 actuated by the gases issuing from exhaust pipes 46, 46 to circulate cooling water through pipes 55, 60, 55, B5, radiators 54, 54' and water jackets 21, .21, the radiators being cooled by the incoming air rushing past them into the intake funnels 48, 48' during operation.

The air compressed in intermediate chambers 41, 41 is primarily fed to the interior piston chambers 30, 30 to a limited extent through piston apertures 6|, 6! past internal leaf spring valves 52, 62'- and thence through piston outlet ports 64, 64 into cylinder passages 53, 63 controlled, respectively, by pressure responsive valves 55, 55'; the compressed air thereafter passing not only the latter valves but fuel nozzles 40, 40 and entering cylinder chambers 32, 32 through ports 42, 42' already referred to above. During operation, the air pump piston 24 obviously furnishes more compressed air than can possibly be used for forming the explosive mixture in the internal combustion cylinders, the excess of this air being the main product of the apparatus as a whole when designed to furnish compressed air. The main bulk of the air thus delivered issues from cylinder chambers 41, 41' through main supply pipes 66, 66 by way of end ports 61, 61 past leaf spring valves 68, 68 limited in outward movement by stop members 69, 59, the'air supplied being useful for any purpose already well established for compressed air. In the present case, however, the air is of such ample volume as to be particularly suitable for jet propulsion of boats and aeroplanes or for driving pneumatic tools and other devices without heat.

While the pressure is produced in supply pipes 66, 66, some of the air will pass upward through pipes l0, l0 and control valves H, H as well as check valves I2, 12' into storage tank 13 used for storing starting air for the engine. This, of course is only a temporary drain on the compressed air supply which is quickly replenished when the engine has run a short time, and as soon as the pressure rises in the tank as may cause the air supply in pipes 66, 66' has a high pressure, the safety valve 15 will allow the excess to escape and thus preserve the tank intact,

as seen in Fig. 6. 1 An additional source .of compressed air for the tank is provided in end recess chambers 16, Iii resulting from the mutual interfitting of piston shoulders 11, ll within end plate shoulders", 18' in recesses 19, 19' at the ends of the strokes of intermediate pump piston 24. When viewing Fig. 4, it will be seen that with the piston moving toward the left, shoulders I1 and 18 besin to overlap or engage, so that recess chamber .15 quickly acquires a high compression of the air trapped in said chamber and thereby pro- .Vides an air cushion which effectively prevents the piston from striking end plate I1. In similar fashion, when the piston returns to the right to occupy the position shown in said Fig. 4, the shoulders 11 and 18 meet and trap air in recess chamber 16 so as to form another air cushion on the right side of piston 24 to softly stop it for the return movement toward the left, etc. Each of end plates l1, H is provided with an escape valve 8| slidable in a valve casing 82 having its interior chamber 83 communicating with the cylinder recess chamber 16 just described by a passage 84, the valve chamber also communicating through branch pipe 8!! and valve 12 with tank 73. The valve 8! is urged toward passage 84 to close the same by a compression spring 81 which may be manually regulated for degree of pressure by manual screw 88, so that only when the air cushion in the recess chamber 16 attains a predetermined high compression will the, valve open and admit air to tank 13. In similar fashion, the end plate IT has corresponding, parts with prime references. It is understood, of course, that the air cushion at both ends is 'not allowed to collapse by letting the air into the tank as the pressure rises in chambers 16, 16' but only the excess above a certain high pressure, and at the same time the main pump piston 24 is softly stopped at both ends of its strokes so as to prevent mechanical contact of the piston with the end plates.

When the engine is to be started, a further valve equipment is called into play, also assoct- .ated with the end recess chambers just described, or rather with the end plates in the projecting shoulder portions l8, 18 of said plates which dorm the outer sides of said chambers. Thus, in each end plate is an inwardly opened valve 89 (Fig. 6) seated in the inner end of valve casing 30 Within which is a valve chamber 9| communi eating by passage 92 with a longer passage 93 in the end plate, which is connected in turn to fora-rich pipe 94 and through control valve 96 with tank .13. It may be noted at this point that check valves H, H, serve to prevent escape of pressure fluid from the tank toward supply pipes 66,. 66' (Figs. 4 and so that the, only normal escape for the air in the tank is through the :control valve '96 and branch pipes 94, 94' toward aralves 89, 89' in the end plates. The valve stem ,9! of valve 89 is in each case provided with a disk piston 91 in rear valve chamber 98 and urged outwardly by a spring 99 to effect normal closure at the valve. Below the latter ,is a smaller valve 1M, opening into the previously mentioned passage, in the end plate 11, extending through (a waive casing Ml whoseginterior valve chamber m is connected to therea-r portion of valve charm her 98 by pipe- !03. Externally the valve cash}! ml supports a spring I04 which bears against the underside of stem head I05 of valve "10, t ndius to close said valve when the head is not depressed by. external means. The co esp ndin parts associated with the other end plate ll have the same references mentioned but primed.

Upon both ends the en ine arries the starting levers I06, 106' (Pics. 2 and 3) pivoted at fll' for example so as to be rockable to re is er the ends I08 into position on stem head 10.5, and in the case of. valve 1100-, upon its stem head to depress the valve lull or Hill. as the case may be, and thereby let pressure fluid from the tank through passage 93 enter the r ar val e cham er s8 and thereby cause disk piston 91 to shift in.- wardly to open valve 89 an in this manner allow the pressure fluid in passage 93 to enter directly int p mp hamber 41. .It should be stated th when one of th tartin levers is pera ed to open one of the valves [00, the other'is shifted in the opposite direction for the moment to avoid openin the other cor-responding va e un il he pump piston 24 has made a stroke, and then the other lever is shifted to operate its adjacent-valve m0 while the first starti g lever is shif ed the opposite way to avo d t valve MB, unti the pis on makes its return stroke durin he starting of the engine.

How v r. at the same time l er operated, its fork 109 which is moun ed on he pivot. shaft I01 of said lever is likewise shifted with the latter, the fork being located in a position to en'- ase up n both s des of a pin 1 l0 m v b erin a slot H1 in end plate I1 and dire tly conne ted to a crescent-shaped valve plate HZ slidable upon the inside of said end plate "Thus when leyer I06 opens valve I00, its associated .fork will also shift plate M2 to close passages 61 so that pres.- sure flu-id entering the chamber 41 from the tank past valve 89 will not escape but serve the intended purpose of driving piston 24 toward the ri ht through its first stroke into the pos ion shown in Fig. 6. Assumin that the piston is first located at theleft when lever I06 is operated, the air ent rin y valve 89 immedia ely a ts on piston '24 to drive it toward end plate I1 as already in ated. causing it to compress air between the same and end pl ll at lea o a limited extent and which is forcedto enter partly into piston chamber .0 th u h po past valve 62' until said port is cu ofi f om ch mber 4'! by he en plate dur ng ightward travel o the piston. Of course. th s n c a ber .310 initially receives ascharge of compressed air from chamber 4.] through port :61, but any case, to; starting the en e itis first n cessa y that valve -98 is open to release the air from tank 13 into end plate-chambers or passages .93, 93'. If electric switches 35, 35' are closed, current from sources 34, 34' (which may be a single current sourced; desired) will immediately begin heating hot wires .36, 36 in the cylinder ends and then maintain said wires red hot to be effective to ignite the combustible mixtures of air and fuel in said cpl, inders for starting.

When h p ton .24 has thus en r en toward the right by the first charge of pressure fluid from ta 3 to c p h pos tion ffset-d1; is instantly re y f r a e u n str ke toward the left end plate 11, inv v ng -a.:reversal o he first-starting lever I66 is returned to initial position, which allows valve I88 to close, and instead, lever I66 is shifted to open valve I6 at the right and thereby cause pressure fluid to pass through chamber I02 in valve housing NH and through pipe I03 into valve chamber 98' to drive valve piston 97 and its associated valve 89 to open position and allow pressure fluid to enter pistonchamber 41' past valve 89', thereby driving piston 24 back again toward left end plate I'I.

While piston 24 is first being driven toward the right as already described, the inlet port 6| will be uncovered as it leaves said end plate I'I thus allowing pressure fluid to enter piston chamber 30 from cylinder chamber 4i, later to be supplied to cylinder 32 at the end of the stroke through piston outlet 64, passage 42, past fuel nozzle 40, and while taking up fuel from the latter enters cylinder chamber 32.

-When the piston is then powerfully driven toward-plate I? just mentioned by the compressed air from tank I3 past valves 89' and I60 entering chamber 4l','the air and fuel mixture in cylinder chamber 32 will be compressed, the piston port 6I being then closed by travel of piston 24 toward the left end plate. The mixture in chamber 32 is quickly and fully compressed and also ignited by hot wire 36, and then drives 28 toward the right by the resulting explosion in chamber 32, piston 24 associated with said piston 28 simultaneously compressin the air in cylinder chamber 41, while end piston 28' compresses the air and fuel mixture in cylinder chamber 32 which has just been supplied'from piston chamber 30 past nozzle 40 by way of cylinder port 42. As wire 36' is also heated, the compressed fuel and air mixture in cylinder chamber 32 ignites and drives the piston 28 toward the left. The starting levers are jockeyed back and forth once or twice in alternation, and need not be used further, but as ignition begins to occur by mere compression, switches 35, 35 may be opened to allow hot wire's 36, 36 to cease glowing. At the same time,

valves 89, 89 are no longer necessary for supplying air from the storage tank to cylinder chambers' 32 and 32, and remain closed, the air thereafter being compressed in chambers 41, 4'! feeding in sufiiciently into piston chambers 38, 36 and by ports 42, 42 leaving said chambers and being transferred to cylinder chambers 32, 32'

"with fuel from nozzles 46, 40 during transfer, so

that a constant supply of combustible fuel mixture' is thus provided the cylinder chambers at the ends which are compressed and exploded by the compression. This results in a continuous 2 oscillation of the composite piston 28, 24, 28 which very quickly gains in frequency and speed so as to oscillate at a high rate of oscillations per minute, which rate, however can be nicel controlled. It has been shown that the air introduced into the main cylinder chambers 41 41' enters through slots or passages 52, 52 in end plates l1, H from intake members 48, 43 through slots 49in valve plates 55, 56' (Figs. 2, 4 and 5), and due to the fact that the latter plates 8 necting shaft II I in the latter case; this shaft interconnecting the two gear segments H5, H5 so that when lever H6 is partly rotatedwith its segment H4, the shaft H'I and segment H5 and its meshing segment H4 will also be similarly partly rotated. This partial rotation causes an arcuate sliding movement of valve plates 56, 50. between intake members 48, 48 and end plates 11, H, with corresponding opening or closing of slots 52, 52 in the latter plates according to the degree in which slots 49, 49 in valve plates 50, 50, register therewith, Naturally, when only a small amount of air is allowed to enter the cylinder chambers 41, 41', the amount available to enter piston chambers'36, 30' and thereafter to issue therefrom past the fuel nozzles 40, and into said cylinder chambers by way of passages 64,43 and 42 is limited, with the result that only a moderate speed and rate of oscillation of piston 24 as driven by pistons 28, 28 is possible.

During the operation of the engine as above outlined, the exhaust gases leaving the cylinders26, 26' by way of ports 63, 63 in chambers 32, 32 pass out through pipes 46, 46 already mentioned to drive exhaust fans or turbines 51 which in turn drive water pumps 56, the drive rotors 58 being directly connected to pump rotors 59 and circulate cooling water through cylinder jackets 2?, 2I-. One feature which also contributes to the smoothness of operation is the tension present in valves 65, 65' (Fig. 4) the springs H8, H8 being adjustable by manual adjusting screws I I9, H9, the degree of pressure exerted by the spring on the valve in each case determining the pressure of the air from piston chambers 36, 30 which will be sufficient to open said valves and pass onward through ports 42, 42 into cylinder chambers 32, 32. The density of the air and fuel mixture is thus largely determined by the mentioned valves and the adjustment of said springs H8,'I I8.

While crescent valve plates and I I2 are somewhat similar, their functions are rather different, plates 56, 50' determining the amount of air which is initially permitted to enter the engine cylinders,

, while plates H2, H2 serve temporarily to close first one cylinder chamber 41 and then the other 4'1 during starting, but the are partly rotary in slidable manner against end plates lI, I'I with plates 56, 50' held slidably by bolts I20, I26, etc., (Fig. 2) in plate slots I2I, I2I, while plates H2, H2 are similarly held captive to plate I1, I'I upon the internal sides thereof by bolts I22, I22 (Fig. 4).

On the other hand, it is quite obvious that the piston 24 and its associated pistons 28, 28 should not be permitted to rotate during operation, but instead means must be included to ensure that piston ports 64, 64', for example will always register with cylinder ports 43, 43' at the ends of the piston strokes. For this purpose piston 24 is pro videdwith aligned rods I23, I23 (Fig. 6) secured rigidly to the piston and sliding in sleeves I24, I24 fixed on end plates H, H, thus causing the piston to oscillate or reciprocate from one end position to the other without the least tendency to turn or rotate about its longiudinal axis. Fur thermore, definite use is made of the movement of'rods I23, I23 to produce electric currents by surrounding the sleeves in which they slide with coils I25, I25, the rods being of steel or other magnetic alloy such as that known as Alnico so that currents are induced in the coils, the leads I26, I26 of the latter being brought to acumulators or other electrical devices, or even to the hot 15 wires 36,. 36 at starting and thereby eliminate atom-s2 other current sources. It is evident that the guide rods; mentioned maybe enlarged andthe coils likewise, to such size and proportions that their capacity to produce. electric currents forms the main purposev andproduct: of the engine as awhole, the air compressed being then merely intended to. suffice for supplying: the. engine with combustible mixture for its operation.

From the foregoing it: may be noted that: when. the engine has. been started by proper manipulatinnof the starting valves and is: running so. as: to; attain its proper speed to supply air or'electrio current or both; the engine will continue at a steady rate to supply compressed air or electric current; by a high speed oscillation of" its built up or composite piston without rotation of any shaft or flywheel nor sliding of a cross head or movement of any crank. It is also clear that by merely controlling the amount of air supplied to the engine, its speed and the. resulting output are directly controlled and determined within a wide range of possible speeds and" output volumes, as desired and as conditions require.

It is also readily seen that the invention is susceptible of modification even further so at one extreme, it delivers compressed air at high pressure and for this purpose, the guide rods may be replaced by other means as will now be discussed'morefully. Asmaybe noted in Figs. 9 and 10; the base equipment is the same as before stated, while the end plates I21, I21 differ somewhat from plates: IT, IT, but are connected with their internal passages I28, I 28' communicating by pipes 85, 85 and valve 96 with tank 13, the

latter being in this case used for storing the high .form with the same a slidable cylinder uniton base IrZ while being directly supported on baseplatefixed to said end plates. The latter may have either secured thereto by bolts, or actually cast integral therewith a pair of cylinders I29; I29 in all respects similar to cylinders 26", 26' and hence, their cooling jackets and other appurtenances. which may be assumed as associated with said cylinders are superfluous to show fully and discuss here. The pistons 28, 28" as well as intermediate block 29 have the novel pump piston I30 mounted thereon with its internal flange I3I clampedbetween said pistons 28, 38"", but piston I 30 is substantially fiat and has upon each side a pair of hollow pistons I3 2, F32." secured thereto by screws or bolts I33, I33, only one upon each side appearing in the sec-- tion of Fig. 10. These pistons are actually held rings I34, I3 which are retained by said. screws, this constructionmaking for a certain adjustabili ty that is desirable in this engine, the pistons extending slidably through the end plates into cylinders I, I35 secured externally upon said. end plates by screws I36, I36.

I-t-is shown in- Fig. 9 that the two cylinders I35, I35 are located in balanced opposite positions upon the end plates, the other cylinders being indicated in broken lines which are. attached to the end plate I21". On the other hand, in this engine there is nooutlet plate like plate or member II3 present, nor internal plate II2 to control the air output, as instead; passages I=3'I{. I31 in piston I230 allowthe air being compressed at each stroke of-said piston to press open valves I3fl ,..t38i", according? to. which side of the piston is; compressing the. air in. chambers: At; 451" and, thus cause the compressed. air tQzbB. injected intothe: hollow' pistons I32, I32", as the case may be. The airinjected in this manner is released bythe end valves; 139', I39 into cylinders I35, I35, whence these pistons force the air charge thusreceived outv through valves I40, M0. into pipes I4 I, I4I" and past: valves I 42, M2" into tank I3 for storage. The springs I43, Hi3; serve to hold valves I38, I38" closed. until, the compressed air, is of sufiicientl-y high. pressure to: form; aproper charge to introduce into theholl'ow pistons and their cylind'ersi for transfer up to thestorake tan-k. Like;- wise, springs I443, I44" tend to close valves I33, I39." so that the ends: of pistons I32, I32 will be unbroken. to; force. out the air charge in cylinders I35, I35 as efiiciently as possible past valve I; I40 to the tank- In similar fashion. springs I45, I 45 are sum;- ciently powerful to close valves I40, I" when the pressure in end cylinders I35, I35 is not-materially greater than the pressure feed pipes I41, I4I'" leading to: the storage tank just men.- tioned. The operation of the end pistons 2.8, 20" with their internal chambers 30, 30", inlet ports 6|, 6i and outlet ports 64, 64 is the same as already described; but the inner sides or faces o-f'end. plates; I'i 'l', IZi'I" and both of the working faces of piston I30 are substantially flat, except for the. hollow pistons'2 3; 2B" projecting axially therefrom into. the end plate cylinders. The.

- mentioned piston. I30 is braked at the end of'eaclr stroke. by the air compressed between said piston and the end plate for'the'moment adjacent thereto, but the amount of air thus caught against the end plates in chambers 41-, 41" is: that actually caught ahead of the valve structures I40, M6 in valve inletv passages: I31, I31", respectively, when these valves begin to projectinto'the. same. The amount of such air which it is intended to serve as an air cushion is regulated by the manually set needle valve member or screw I41 in valve- MB, and F41 in I46 by which to allowa predetermined leakageof compressed air frominlet. chambers. 031, I31 through side apertures I36; (see Fig. ll into the pump chambers '41-;v 41. past. the needle valve members E4 1, I 41 and. thereby: brake or cushion piston I30 as it ap-- proaches: the end plates so as to prevent the lat-- ter piston from striking said plates. This cu'sh ioning effect is the same at each end of'the piston i stroke and inno case does it represent lost power;

but rather'accum-ulated energy which isiinmedi ate'ly returned to: the piston to send the same in the opposite direction. However, in this conany further extent than to let pass the main bulk of the compressed airfrom cylinder chani bers' 4' 1, 412'"; after which these valves close and. allow the residue to remain as just described, in order tov cushion the-piston strokes. Naturally, theleakage valves could be arranged to cooperate with and project into blind chambers, if sodesired. The apparatus is: thus arranged to oper ateat' the highest possible efliciency without actualrcontaot; of piston I30 with either end plate at; any time, the pump delivering the air com-- pressed: to: the 'holl'ow pistons and the latter further compressing the air to a higher degree and delivering the high pressure air thus re-- SUItiT-IgrllQ-th storage tank.

In the. formxof' the apparatus'shown in. Figs. 9- and; 1-0:, the starting valves. I'llIl, I500" areinclud'ed ontheendlplateszand communicate with the'plate chambers I 2 8;. I-28"andr are connectedby men-- 11 tioned pipes I03, I03" to rear piston valve chambers 98, 98 in order to'allow compressed air from storage tank I3 to pass said starting valves from saidplate chambers into rear valve chambers 98,

98 when valve heads I05, I05 are alternately bers 41, 4'! alternately to'start piston I to reciprocate. i

- When the latter piston begins to operate regularly, andassuming that the hot wires 36, 36 are supplied with heating current and the engine otherwiseprovided with water cooling, etc., as already described in connection with the engine of the former figures, the compressed air produced by reciprocation of the main pump piston I30 is partly directed through ports 6|, BI and piston chambers 30,130 to end cylinder chambers I45,

I45 and there exploded or fired to drive pistons 28, 28' in much the same manner as already set forth in the foregoing description of Figs. 1'

through 8. The main bulk of the compressed air of course not delivered to the outside through any delivery pipes suchas '66, 66', but is, as already intimated, insteadalternately forced past valves I38, I39 in hollow piston I32 and valves I38, I39 in piston I32-into pipes I4I, MI and past check valves I42, I42 into storage tank T3 whence compressed air under high pressure may be supplied to the outside through pipe I48 by way of control valve I49 for running pneumatic'motors and other devices.

When starting the engine, there are certain features somewhat different from the starting of the engine of formerFigs. 1 to 8, as now the air first compressed in cylinders I 35, I is not used but must be disposed of before the appa ratus can attain proper operation. For this purpose, valve casings I50, I50 are connected to the interiors of cylinders I35, I35 at the inner ends of said casings, while in the latter are valve pistons I5I, I5I integral with valves I52, I52 which are opened by the air pressure exerted on pistons I 5|, I5I' when starting valves I00, I00 are opened by depression of their outside heads I05, I05, as the air entering rear valve chambers 98, 98 not only shifts valve pistons 91, 91' to efiect opening of valves 89, 89, but some of this compressed air also, passes down pipe I53 and across in upper pipe I53 into valve casings I50, I 50' and shifts valves I 52, I 52 to open positions by pressing upon valve pistons I5I, I 5|, allowing first the air compressed in auxiliary cylinder I35 to escape through casing I50 past valve I52 and out to the atmosphere through side port I54 in said casing, and then air in casing I50 from cylinder I35 past the valve I52 and out through the side port in said casing I50 at I54. As soon as the engine'has begun to run without manipulating the starting valves I 00, I00 "andno longer requires encouragement from .the'hot wires to explode the combustible chargesxin cylinders I2 9, I29, the relief va1ves-jI52, I52 will be automatically closed by their springs I55, I55, the other valves 89, 89' and I00, I00 also being closedJ-by their springs, so that control of the running ofthe apparatus passes to manual leverI-IB operating the crescent-shaped valve plates :50, 50" directly controlling the intakeof air into the chambers 4.1,-

41. The main principles of both forms of my invention are the same, and modification refers mainly to means for obtaining the desired product, compressed air of moderate pressure, or compressed air of moderate pressure and also electric current, or electric current alone, or high pressure compressed air, etc. The machine is likewise capable of fine regulation, even while running, and is especially capable of running at very high speeds with very high frequency of reciprocation of the composite piston, resulting in unusually high efficiency for minimum of weight of engine. It is evident also that the invention in its practical embodiments is capable of wide use and applications in various lines of work.

' The apparatus described may be made of any metal, alloy or combination of metals, as found desirable, and other variations and modifications than those shown or suggested may be resorted to, and parts may be used without others within the scope of the appended claims.

Having now fully described my invention, ,1 claim:

1. A free piston internal combustion engine, including in combination, a pump casing having a cylinder casing connected directly to each end thereof, a pump piston reciprocable in said pump casing and having a further piston member connected to each end thereof and extending into the end cylinder casings, ignition means associated with the latter for initially igniting explosivecharges of fuel and air in starting the engine operating, inlet ports for admitting air into the ends of the pump casing independently of said end cylinder casings and manually controlled valve means for controlling the ingress of the air into said pump cylinder casing, internal valve means within said pump cylinder casing preventing escape of air from the interior past said manually controlled valve means, exhaust pipes leading from the end cylinder casings independently of, said pump casing, valve controlled fuel supplymeans connected to the end cylinder casings,"

means for supplying predetermined amounts of compressed air from the pump cylinder casingto the interior of the end cylinder casings, said last mentioned means including a partition dividing an internal chamber in one end' piston member from an internal chamber in the other end piston member, an air inlet port in each end piston member spaced a limited distance from the partition and having an internal valve means for preventing escape of air from the internal chamber in the piston member involved, the air inlet ports in the end piston members being periodically exposed to the interior of the pump piston casing to receive a charge of compressed air from the same, and a further port in each ..main bulk of the compressed air from said pump cylinder casing to a storage tank or an air supply line.

2. A free piston internal combustion engine, in-

cluding in combination, a pump casing having a cylinder casing connected directly to each end thereof, a pump piston reciprocable insaid pump casing and having a further piston member connected to each end thereof and extending'into thewend, cylinder casings, ignition means asso ciated with the latter for initially igniting explosive charges of fuel and air in starting the engine operating, inlet portsv for admitting air into the ends of the pump casing independently of said end cylinder casings and manually controlled: valve means for controlling: the ingress. of the air into said pump cylinder casing, internal valve means within said pump cylinder casing prevent ing escape of air from the interior past said manually controlled valve means, exhaust pipes leading irom the end cylinder casings independ ently' ofisaid. pump, casing, valvecon-trolled fuel supply means connected to the end cylinder casings; means for supplying predetermined amounts of compressed air from the; pumpcylind'er casing, to the interior" of the end cylinder casings, said last mentioned means including an an" inlet port in each end piston member spaced a short, distance from the pump piston and leading to: anlinternal chamber in each end piston membenan' internal; valve member in each chamber preventing escape oiair' from the: same through the air inlet port thereof, a further air port. in each and piston member spaced a limited distance from the outer end of the latter, a corresponding port the wall of each end cylinder casing disposed in a position to register with the further air port in one extreme positionof the piston members, a second port in the wall of each end cylinder casing connected to; the corresponding port therein, a fuel nozzle disposed in association with each said second port, the second: port inaeach, case beingv closed: by the respectively adjacent end-.piston member: except in; the; ex.- treme operated position. of the: latter, and valve. means for controlling the flow of air from the internal chamber in each end piston member out through the further air port thereininto the corresponding cylinder wall port past the valve means through the second port in the cylinder wall into the outer end of the end cylinder casing to form a fuel charge and scavenge exhaust gases from said casing, there being valve controlled ports in the pump cylinder casing for conducting the main bulk of the compressed air from said pump cylinder casing to a storage tank or an air supply line.

' 3. A free piston internal combustion engine,

including in combination, a pump casing having a cylinder casing connected directly to each end thereof, a pump piston reciprocable in said pump casing and having a further piston member connected to each end thereof and extending into the end cylinder casings, ignition means associated with the latter for initially igniting explosive charges of fuel and air in starting the engine operating, inlet ports for admitting air into the ends of the pump casing independently of said end cylinder casings and manually controlled valve means for controlling the ingress of the air into said pump cylinder casing, internal valve means within said pump cylinder casing preventing escape of air from the interior past said manually controlled valve means, exhaust pipes leading from the end cylinder casings independently of said pump casing, valve controlled fuel supply means connected to the end cylinder casings, means for supplying predetermined amounts of compressed air from the pump cylinder casing to the interior of the end cylinder casings, each end plate having an auxiliary cylinder casing projecting therefrom and the pump piston having a hollow piston upon each side thereof projecting into the auxiliary cylinder casingupon its side, valve means for passing compressed air from one side of the pump piston through the hollow piston on the other side intothe auxiliary cylinder casing on'said other side but preventing passage of air in the opposite direction' through said piston, similar valve means for passing compressed air into the other hollow piston from the side of the pump piston opposite thereto and preventing return. flow of air therethru, and end valves in said auxiliary cyl inder casings connected to an air storage tank or compressed air supply line for feeding compressed air from said casings to said tank or line 4. A. free piston internal combustion engine," including in combination, a pump casing having a cylinder casing connected directly to each end thereof, a pump piston reciprocable said pump casing and having a further piston member con nected to: each end thereof and extending into; the

end cylinder casings, ignition means associated with the latter for initially igniting explosive: chargesoi' fu ei and air starting the engine op--- erating, inlet ports for admitting" air into theends ofthe pump casing independently of said end cylinder casings and manually controlled valve, means for controllingthe ingress: of the air into said pump: cylinder casing, internal valve means within said pumpcylind'ercasing prevent ing escape of air from the interior past said manually controlled val ve means, exhaust pipes leading from the end cylinder casings independently of said pump casing, valve controlled fuel supply means connected to the end cylinder casings, means for supplying predetermined amounts of compressed air from the pump cylinder casing to the interior of the end cylinder casings, a leakage valve structure secured in projecting position upon each side of the pump casing, a manually adjustable valve member mounted in each mentioned valve structure hav: ing a valve seat exposed to the interior of the pump cylinder casing at the point of greatest projection of the valve structure into the same, the valve member cooperating with the valve seat in each case, and each valve structure having at least one side port adjacent to the wall of the pump casing upon which it is located, and the pump piston having recesses upon the sides thereof into which the valve structures at the end of the piston strokes will fit and serve as cushioning means preventing the pump piston from striking the ends of the pump casing, there being valve controlled ports in the pump cylinder casing for conducting the main bulk of the compressed air from said pump cylinder casingto a storage tank or an air supply line.

5. A fre piston internal combustion engine, including in combination, a pump casing having a cylinder casing connected directly to each end thereof, a pump piston reciprocable in said pump means for controlling the ingress of the air into said pump cylinder casing, internal valve means within said pump cylinder casing preventing escape of air from the interior past said manual ly controlled valve means, exhaust pipes leading from the end cylinder casings independently of said pump casing, valve controlled fuel supply means connected to the end cylinder casings, means for supplying predetermined amounts of compressed air from the pump cylinder casing tothe interior of the end cylinder casings, the manually controlled valve means including a slidable plate having at least one slot portion therein-adapted in one position to register with the inlet-ports at each end of the pump cylinder casing; the internal valve means controlling the same inlet ports and consist of leaf spring valve mem bers, there being valve controlled ports in the pump cylinder casing for conducting the main bulk of the compressed air from said pump cylinder casing to a storage tank or an air supply line.

6.-A free piston internal combustion engine, comprising a pump cylinder casing having a pump piston reciprocable therein, two end cylinder casings rigidly connected to said pump cylinder casing, two pistons connected to the pump piston and extending into said end cylinder casings, air inlet ports in the end walls of the pump casing, means for regulating the ingress of air through said ports, means preventing escape of air from the pump cylinder casing out from said ports, means for passing compressed air periodically from said pump cylinder casing into the end cylinder casings, means for exhaust ing spent gases from said end cylinder casings,

means for delivering compressed air to the outside from both ends of the pump cylinder casing through air supply ports, means for preventing ingress of air into said pump cylinder casing through said air supply ports, an air storage tank, air pipes connecting the engine with the air tank, and valve means controlling supply of air from said tank to the interior of said pump cylinder casing for starting said engine.

7. A free piston engine according to claim 6, in which the pump cylinder casing has a pair of end plates spaced apart and supporting the end cylinder casings in axial alinement with the pump cylinder casings.

8. A free piston engine according to claim 6, in

which the pump piston and the end cylinder pistons include an internal partition member, a pair of end pistons secured upon the ends thereof, and a disk piston member mounted upon the inner ends of said end pistons and having an internalflange portion extending in between said inner ends of the end pistons and thereby retaining said disk piston member in fixed relation to the latter pistons.

UNO EKBLOM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,132,381 Porter Mar. 16, 1915 2,215,326 Janicke Sept. 17, 1940 2,232,631 Renick Feb. 18, 1941 

